A blog about scientific material culture.

Over the past couple of months, I’ve been building a 3d-printed model of a nineteenth-century psychological instrument used to demonstrate the nature of colour perception. The model, and, to a certain extent, the effects that it creates, can be seen in this video, though the actual blending effect is smoother and more coherent than the camera is able to show:

The project is partly a way to explore Toronto’s place within the early history of psychology. The instrument, sold beginning around the turn of the twentieth century by the Zimmermann workshop in Leipzig Germany as Farbenmisch-Apparat nach Kirschmann (“Colour mixing apparatus after Kirschmann’s design”), was devised, in part at least, by August Kirschmann (1860-1932) a German-born scientist who led the recently founded Psychological Laboratory at the University of Toronto from 1893 to 1908.

Kirschmann’s apparatus (left) as it appears in the 1893 Zimmermann catalogue of psychological apparatus. The illustration shows only part of the apparatus which I’ve taken to calling the “masking wheels”. Its description says that the apparatus resembles item 12, the “Rotations-Apparat mit Doppelachsen”, a coaxial disk spinner shown on the right. Images are from the digitized catalogues of the Max Planck Virtual Library.

The original instrument, which appears to incorporate two nested axles, would require a machinist’s skills and tools to reproduce. The model is made from various 3d-printed parts, copper gas pipe (easily cut to length with a 10$ pipe cutter), skateboard bearings, and various common nuts and bolts. It is meant to be very easy to make. It isn’t meant to replicate the appearance of the original instrument but rather to function in a similar way.

An exploded view of the model. 3d-printed parts are indicated in blue. Using a combination of 3d-printed fittings and other parts seems to make good use of current consumer level FDM printers.

Colour at the turn of the twentieth century

Over the late nineteenth and early twentieth centuries, the practice of experimental psychology was taking hold in laboratories across Europe and North America. The sensory physiology of colour perception was an important area of research. Sight is a particularly important channel for gathering information about the world. Various forms of colour blindness, for instance, provided clues towards understanding the physiology of sight as well as an important example of the varieties of individual sense perception. For some, experimental psychology also promised a new avenue from which to approach philosophical questions about beauty and aesthetic pleasure.

A photograph of Kirschmann taken while he taught at the University of Toronto. Image provided by UTARMS.

August Kirschmann did his graduate studies in the Leipzig laboratory of Wilhelm Wundt (1832-1920). Wundt is generally considered the founder of experimental psychology as a discipline distinct from philosophy on the one hand and physiology on the other. Kirschmann’s thesis, completed in 1891, explored visual phenomena such as brightness and colour contrast. In 1893, Kirschmann came to Toronto to serve as a laboratory assistant in the recently-established Psychological Laboratory at the University of Toronto. The Laboratory’s American founder, James Mark Baldwin (1861-1934, also a former student of Wundt) had departed that year for a more prestigious position at Princeton University. Kirschmann, who at first knew little English, found himself in charge of the new laboratory. Over the next decade and a half, numerous students at the laboratory took up Kirschmann’s investigations into colour.

A material culture of colour

The practice of experimental psychology depended heavily on the development of specialized instrumentation. While working as an assistant in Wundt’s Laboratory, for instance, Kirschmann co-authored a paper on the control hammer, an instrument used to calibrate the Hipp Chronoscope, an important tool for precision timing. His graduate research produced at least two technologies: a means to produce near monochromatic light using coloured filters, and a simple photometer. Both were elaborated during his period in Toronto and were adopted by other experimenters.

He also, over the course of his career, created several instruments that were put into commercial production by the Zimmermann workshop in Leipzig. The colour mixing apparatus, which he developed during his time in Toronto, was one of these. From this perspective, the instrument can be seen to represent a process through which the newly-established laboratories in North America began to contribute to the material culture of experimental psychology.

When scientists began performing quantified experiments on the nature of colour perception in the nineteenth century, they faced the challenge of how to standardize colour and lighting in such a way as to produce results that were credible and reproducible. Among the most common of the instruments used to study and teach about colour vision was the spinning disk, of which the colour mixing apparatus is one, somewhat elaborate, example.

The value of these instruments was straightforward: Physically mixing artist’s pigments to produce a given colour is a cumbersome process. Mixing spectral colours—that is colours obtained through the diffraction of white light—requires complicated equipment that is (or at least was) impractical to use in an experimental setting. If, on the other hand, two or more shades are painted on sectors of a disk, and the disk is spun with sufficient speed, the shades will appear to blend into an even mix of the constituent colours—one example of the flicker-fusion phenomena.

Spinning disks, in various forms, represent a key part of the material culture of early experimental psychology and are well represented in the early catalogues of scientific instruments. Elsewhere, I’ve discussed the variable colour mixer, an instrument which allowed experimenters to vary a blend of colour on a spinning wheel in precise increments—the U of T psychological collection contains several of this type most of which were built locally. With such an instrument, an experimenter could, for instance, probe the threshold of the eyes sensitivity to colours of different wavelengths under different lighting conditions—a phenomenon known as the Purkinje effect.

Two variable colour mixers. The instrument on the left is a precision experimental instrument made by the Zimmermann workshop in Leipzig, Germany most likely in the first decade of the 20th century. The second instrument was likely made in a workshop at the University of Toronto.

Whereas the variable mixer was, by design, an experimental instrument, Kirschmann’s coaxial mixer was a didactic instrument meant to demonstrate the constituent colours of white light as well as various phenomena that occur when mixing colours on a spinning disk. Like other instruments from the period, for instance mineral tubes which fluoresce when a current is applied, it is meant both to demonstrate a scientific phenomenon and to provoke an aesthetic reaction by showing “surprising phenomena” (überraschende Erscheinungen).

Remaking an instrument

A basic colour wheel is a simple machine. Art students studying colour theory are still assigned experiments that involve spinning coloured disks on electric screwdrivers or kitchen mixers. Kirschmann’s coaxial apparatus is slightly more complicated since it involves two disks spinning at different rates. The “masking wheel” spins in front of the “colour disk”, hiding a certain portion of the coloured wheel and establishing a mix of colour. The slight difference in the rate of rotation means that the portion of the colour disk viewed through the holes on the masking wheel changes from moment to moment. This creates a colour changing effect that depends on the type of masking wheel—the Zimmermann catalogue shows six different wheels, I have so far recreated five of these.

The main challenge in building the model was a lack of information . When I started the project, my only source of information was a very general description of the instrument found in the digitized Zimmermann catalogues of the Max Planck Virtual Library. These also provide the black and white illustrations shown in the second image of this post. No historian that I had spoken to at that point had seen one of these coaxial mixer.

Based on this information, I more or less understood how the instrument worked and set about drawing up the 3d printed fittings using the SketchUp software—an easy-to-use 3d modelling program whose basic version is free. Midway through this process, I had some very good luck. Looking around a Department of Psychology storage room I happened to open an unmarked wooden box and discovered (or rather rediscovered since members of the earlier UTMuSi cataloging project were aware of it) a version of the coaxial colour mixer. I have since catalogued it.

Instrument 2015.psy.160 in the UTSIC collection, the Kirschmann Coaxial Colour Wheel. Note that the disk showing simultaneous complimentary colours has been recreated in a different, perhaps improved, format. The model provides an opportunity to study the difference between these two disks.

At first I somewhat carelessly imagined this instrument to be a prototype or a specially-made version of the instrument shown in the 1893 catalogue. Later, as I went through the digitized catalogues in the Virtual Museum in more detail, I discovered that this was a later version—a model made in the form of a lantern slide which was meant to be placed in front of a slide projector to be shown to a classroom of students. This instrument appears in the 1912 Zimmermann catalogue. It will take substantially more research to determine precisely when these instruments appeared since the collection of digitized Zimmermann catalogues in the Max Planck virtual library is incomplete.

The version of the Kirschmann coaxial colour mixer used with a projector. This image is from the digitized catalogues of the Max Planck Virtual Library.

This object in the UTSIC collection provided a wealth of information such as pulley ratios and the precise shape of the mask disks. It also showed the colours involved and their arrangement though this is something of a guess since the pigments may have faded unpredictably with time and since the original colour wheel was shattered. It allowed me to make a first model of the instrument which shows some version of the effect. I won’t digress on the building and design process here. If there’s any interest in recreating it, I can post some detailed instructions along with various templates and the .stl files for the 3d-printed parts.

If I’ve taken something useful from this project, it’s a sensitivity to the material culture of colour as it existed at the turn of the twentieth century and as it exists now. This is a period in which calibrated colour sets were only just becoming commercially available and international standards for colour and illumination had not yet been established. Much of Kirschmann’s research involved advancing the development of accurate colours. I’m slowly putting together a journal article on the subject.

The creation of this model highlights the vast technological development that has taken place in this area. The transparent coloured disc used in the Department of Psychology’s instrument would have been extremely tedious to produce, with each tiny sector cut separately from gelatin sheet and pasted into place with no gaps or overlap. Recreating it was simply a matter of sampling a digital photograph and adjusting the colours to be as saturated as possible. After that, I laid out the coloured sectors in a drawing program and then laser printed the image onto transparency sheet. Several layers of colour-printed transparency sheets glued to a disk of thin acrylic (cut from a sheet with a Dremel tool) places a good amount of pigment in the path of the transmitted light—possibly more than was available on the original instrument, though it’s hard to tell since the original gelatin sheet seems to have faded over the past hundred years.

The technologies involved in this recreation process, from the CCD in the digital camera, which captures an accurate impression of reflected light as the human eye would perceive it, to the laser printer, capable of representing a vast range of colour though the process of additive-averaging colour mixing, demonstrate our society’s mastery of colour technology—a process of development whose early origins are, to a certain extent, embodied within this historical instrument.

Aesthetic opinions

As a demonstration instrument, Kirschmann’s colour mixing apparatus is, in certain respects, an aesthetic object. As such, it recalls (maybe a little obliquely) Kirschmann’s curious efforts to reground the philosophical discipline of aesthetics in a rigorously scientific study of human perception. Kirschmann had strong opinions on the subject. In a polemical passage on the subject in a paper published around the turn of the century entitled “Conceptions and Laws in Aesthetics”, he claimed that:

All expressions used in aesthetic and art-criticism which can not, unambiguously and without contradiction, be defined in terms of really simple elements…. are nothing but pseudo conceptions; and all distinctions and classifications into which such expressions enter are illegitimate or pseudo-distinctions; and all alleged knowledge based on such conceptions and distinctions is sham-knowledge; and if the originators and propagators adhere to such expressions after they have realized the truth of what is said above, it is not only sham-knowledge, it is then imposition, deception, fraud.

Experimental psychology was to provide these “simple elements”—basic truths about human perception upon which aesthetic judgments were to be grounded and through which opinions were to be articulated with scientific clarity. This program is apparent in the research carried out at the Psychological laboratory at the University of Toronto. For instance, one of Kirschmann’s graduate students, Emma S. Baker, conducted experiments on colour combinations in order to determine the laws underlying aesthetically pleasing contrast.

Kirschmann’s own aesthetic opinions were conservative. He promoted a kind of visual literalism with regards to the depiction of light—a principle, he believed, that the great painters of the past had maintained implicitly. He wrote that:

By cleverly making use of [the law of contrast, the painter] may even raise the intensities of very small, white, yellow, or orange surfaces so as to give the appearance of a certain luminosity, as for instance, in the case of glowing coals and sparks of a smith’s fire, the illuminated windows in an evening landscape, the Alpine glow, etc. But he should never try to paint the flames of candles, lamps, or torches themselves, or the celestial bodies, for this is, with respect to true reproduction of intensities, absolutely impossible.

Kirschmann appreciated Rembrandt’s “somber brown tone” because “the yellow and orange side of the colour manifoldness (brown is always a shade of yellow or orange) admits of the greatest number of intervals between full saturation and the darkest shade.” The impressionist movement, by contrast, sacrificed

all truths of intensity for a certain mannerism in colours. They paint everything in a kind of purplish gray haze, and they call that impressionism, although such impressions can only be obtained by seeing things in a veiled mirror or through a cloud of cigarette-smoke.

Kirschmann was, like many scientists of his day, something of a polymath. He wrote on subjects ranging from logic, to mathematics, to public education—he was a great promoter of the research model embraced by the German universities believing that North American universities should follow that model rather than emphasizing general education. His forays into aesthetics may be partly explained by the fact that he was a professor of philosophy—the nascent practice of experimental psychology took root in Toronto within the existing Department of Philosophy, as it did elsewhere in Europe and North America.

As with other scientific objects, Kirschmann’s curious demonstration instrument provides a kind of window into the past opening onto a variety of historical themes. It takes us into a period in which practices, developed in the German research system, were being absorbed in North America along with their material accouterments. The study of colour perception was a key area of interest for experimental psychologists. The collection of psychological material at the University of Toronto ought to be considered a key material archive for studying this area. The process of recreating such instruments also deserves consideration as a scholarly research technique.

I am very grateful to Gabby Resch and Isaac Record of Semaphore Maker Labs for help on various 3d printing projects as well as to David Pantalony and Christopher Green for their advice on the history of psychology.

I would also like to thank Michael Spears and Erica Lenton at MADlab at the Gerstein Science Library. U of T students and faculty can use the 3d printers at MADlab for a very reasonable price after taking a simple safety course.

Contents of the Ontario School Ability Test. Presumably it was fabricated in Toronto. The weighted cylinder at the bottom of the photo has come open revealing that it is filled with led shot and cotton padding.

In the context of historical evidence, the distinction between “object” and “text” is somewhat artificial. As any historian of print culture will tell you, texts are embodied in complex material objects (most obviously books) whose design and construction is bound to the history of technology and culture. Objects, for instance scientific instruments, are most often embedded in a web of texts such as research papers, purchasing catalogues, and instruction manuals.

Psychological testing material further obscures this distinction. A typical test might consist of a combination of documents and other standard objects packed together in a sturdy brown box made of wood and particle board. The tests in the UTSIC collection range from stacks of paper documents to puzzles and other artefacts that are, in principle, little different than common psychological apparatus meant to measure physiological characteristics such as memory or reaction time.

The distinction between text and object is a necessary heuristic that is reflected in the ways we care for historical evidence. Generally speaking, artefacts belong in museum collections, texts go in libraries and archives. Psychological tests tend to end up in the latter. The archives of the Centre for Addiction and Mental Health (CAMH), for instance, has an extensive collection of psychological tests. The Center for the History of Psychology at the University of Akron also keeps its tests in a special collection.

The tests belonging to the University of Toronto Department of Psychology seem mostly to have come from a library collection—a number of instructional booklets have been bound with cardboard covers and given library cards. At some point, possibly in the mid-to-late 1950s, the material not already in boxes or cases was carefully bundled in butcher paper and string. It remained in a storage room until the UTSIC project began to examine it around 2009. The UTSIC project has catalogued parts of this collection over the past several years.

Testing material from the Department of Psychology collection. Many tests were sold in varnished boxes. Other material has been bundled together with brown paper and string. A number of bundles have not yet been opened.

Recently, I was given some money from the Hewton and Griffin Bursary for Archival Research, supported by the Friends of the Archives of the Centre for Addiction and Mental Health (CAMH). This has allowed me to spend some time researching and cataloguing this material. The official purpose of my project is to discover the collection’s history, or “provenance”, for instance which library collection some of this material belonged to. Much of what I write here comes from several weeks of initial research.

Drawing Boundaries

In trying to incorporate the psychological tests into a collection of objects, one runs into (what I have come to think of as) the “box of pulleys problem” following a long discussion that took place in the early stages of the UTSIC project: What do you do when faced with cataloguing a box of pulleys, or light bulbs, or weights, or some other assortment of (relatively) mundane objects? You could assign each item a separate accession number, filling a separate condition report, photographing each object and adding it separately to the catalogue. Alternately, you could simply catalogue and photograph a “box of pulleys” and put it back on the shelf until you get an email from some historian of technology collecting research for Lifting the burden of history: A cultural history of pulley manufacture in Lower Silesia.

Such compromises are especially important in a project which depends on temporary research assistant positions and volunteer labour. That labour is better spent adding significant objects to the catalogue than picking through boxes of pulleys. Moreover, numerous minor objects add clutter to an online catalogue and obscure more interesting items from the visitor. My current preference is to catalogue even significant items of identical type and make together while giving them separate accession numbers and condition reports.

This issue becomes especially apparent when cataloguing the psychological testing material. In some cases there are many examples of a single test. In others, a single kind of test has many components. The Dominion school test material, published by the Department of Educational Research at the University of Toronto over the first half of the 20th century, includes, among its many test booklets and instructional pamphlets, 93 examples of a practice test for Kindergarten and Grade 1 students and 146 examples of a Group Test of Learning Capacity for Grades 7, 8, and 9. All of this material is paper. Rather than adding these items to the catalogue, my preference would be to inventory such material in an online spreadsheet that is available through the catalogue website.

The frustrating ambiguity of this cataloguing process can be seen in our previous attempts to catalogue parts of this collection. For instance, someone has catalogued several bound instructional booklets that would have been associated with particular tests. While I understand the reasoning behind this, were I to catalogue this material now, I would likely consider these pamphlets simply as documentation associated with particular objects. We typically file instructional material with the objects rather than adding it to the catalogue.

My bias (and I think the nature of the collection in general) is to privileged objects over texts. The University of Toronto, after all, has a world-class library system and archive but few if any well-supported collections of local material culture. (The JCB Grant Anatomy Museum might count as an unusual exception, but it is not accessible to the public.) Given limited time and funding, my work with the collection will involve photographing and cataloguing the more “object-like” tests while creating an overall inventory of the collection for the use of researchers in this field.

Pathways to the past

Several times I’ve found myself groping unsuccessfully for metaphors to capture a quality that artefacts have of refocusing one’s attention on unfamiliar areas. If established sources or well-known narratives create a familiar topography of the past, then objects often provide shortcuts to new vantage points from which to survey a topic.

The psychological test collection, which contains material spanning the 1920s to the 1950s, is a pool of evidence opening onto a number of areas. One involves a recent past which University experts led the community in establishing rigid norms between insiders and outsiders—a fact reflected in the period’s harsh academic lexicon including terms such as “mental hygiene”, “feeblemindedness”, “subnormals”, and “defective children”. Faculty at the University of Toronto played a leading role in Canada’s adoption of the moral hygiene movement which embodied the xenophobic tendencies of mainstream Anglo-Saxon culture in the nineteenth and early twentieth centuries.

The four remaining Ferguson form boards.

Consider, for instance, the first psychological test that I have been able to examine in some detail: a small and incomplete collection of four “Ferguson Form Boards”. These are essentially wooden puzzles with irregular holes into which wooden pieces are fit. A label at the bottom of several boards reveals that they were constructed in November of 1926. Pencil markings on underside of the boards are notes written by researchers to remind themselves about details of administering the tests. Such cryptic markings are fairly common on scientific objects. Two of the initial set of boards, and several pieces of the surviving boards, are missing. The wood used in three of the boards has shrunk creating noticeable gaps in the surface and causing some pieces to bind. The University of Toronto President’s Report of that year reveals that the boards were created for the Master’s research of Miss J. A. Brown under supervision of Professor Earl Douglas MacPhee. It is unfortunate that no trace of this thesis survives since it might have given details on the boards’ construction, perhaps at a University workshop.

This test, in which subjects were timed in completing boards of varying complexity, were introduced by professor George Oscar Ferguson, Jr. of the University of Virginia in 1920. Ferguson maintained that the test provided an accurate measure of grade level achievement from Grade 1 to the 3rd year of University. [Ferguson 1920, 52] Brown and MacPhee sought to test this claim using a sounder methodology than Ferguson had employed. For instance, rather than choosing students by grade level (a typical Toronto classroom included students of various ages), they selected students based on birth date. Despite finding the tests reliable in the sense that individual subjects obtained similar results over several trials, they found no meaningful correlation between Ferguson test results and other measures of academic achievement. They concluded that the test was clinically useless. [MacPhee and Brown 1930, 34-36]

Brown and MacPhee investigated this test partly in the hope that it might provide a measure of student attainment that was as accurate as existing linguistic tests. This reflected a growing interest in child development and childhood education fueled, initially at least, by public concern over delinquency among public school children. In 1924, a new child study project, supported by the Laura Spelman Rockefeller Memorial and the eugenicist Canadian National Committee for Mental Hygiene (CNCMH), was begun by Dr. William Blatz (1895-1964). The following year, the St. George’s School for Child Study (renamed the institute for Child Study in 1937) was founded at the University of Toronto in a project led by Blatz along with Prof. Helen McMurchie Bott (b. 1886) , later to establish herself as an authority on child development, and Dr. Clarence. M. Hincks (1885-1964), a medical officer in the Toronto School System who had co-founded the CNCMH with C. K. Clarke, Professor of Psychology at the University of Toronto and superintendent of Toronto General Hospital.

The University of Toronto Ferguson Form Boards appeared at a time when the testing of schoolchildren had begun in earnest largely within a eugenic framework which sought to identify and isolate “subnormal” children based on the assumption that low intelligence was associated delinquency. Describing their testing methodology in 1930, Brown and MacPhee noted:

Two typical schools were selected. The basis of this judgement was the per cent of mental defect in these schools. The Mental Hygiene Division of the Toronto Public Health Department has made continuous surveys in the city schools for several years and data were available as to the incidence of mental defect in each of the city schools, and in the school population as a whole. It was assumed that differences in the per cents of subnormals was an adequate measure of difference in the general intellectual level of the school population and two average schools in different sections of the city were chosen. [MacPhee and Brown 1930, 25]

Professor MacPhee’s research projects over the 1920s and 1930s reveal an interest in the classification of schoolchildren. He notably studied “subnormals” in the now notorious asylum for mentally handicapped children in Orillia, Ontario. Brown’s small contribution to this broader project brought her professional success. By 1930, she was employed by the Mental Hygiene Division of the Toronto Department of Health.

The Ferguson Form Boards provide one example of the testing material related to the ongoing study of schoolchildren at the University of Toronto. Dr. William Blatz, the city’s most influential child psychologist who headed the St. George’s School for Child Study from 1925 to 1960, rejected the association between low intelligence and delinquency even while serving as Research Director for the CNCMH from 1925 to 1935. [Raymond 1991, 37] Even so, rigorous testing remained the norm in child study. The Institute’s “Well Children” project report, published in 1956, lists a considerable battery of tests then in regular use, several of which may still be found in the collection.

The psychological tests used, and records kept, at the Institute of Child Study during the period 1953-1955. [Northway 1956, 85-86]

Beyond the testing material used in childhood education, many other forms of research are represented in the testing collection. There is, for instance, a substantial number of tests related to vocational training, evidence of efforts by university researchers to assist industry in selecting and screening employees and in exploring the pathway from classroom to workplace. There is also material related to mental health research. Kira Lussier, currently a graduate student at the IHPST, has described a set of Rorschach testing slides that were likely used for training purposes at the Toronto General Hospital. Ultimately, each of the hundreds of items in the collection is a potential pathway to local meaning.

“Instruments” or “Material Culture”

When the UTSIC project began in 2008, the notion of developing a collection of “scientific instruments” seemed natural. The University had a wealth of impressive nineteenth and early twentieth century objects that fit nicely into this category. Scientific instruments, particularly “charismatic” items of the brass and glass era like microscopes or orreries, have always lent themselves to collection and display. Moreover, within the field of history and philosophy of science (HPS), the theme of “scientific instruments” has provided a useful common point between the two disciplines.

The collection of psychological tests is an example of a type of instrument that does not seem naturally suited to the category of scientific instrument. Whether or not this is true—whether a psychological test is a kind of measuring or mapping instrument like a seismometer or an ECG machine—is the sort of question that a philosopher of science would take on. Regardless, such incongruous objects recall others that cannot in any meaningful sense be called instruments but are relevant to an understanding of the changing culture of science and medicine. Textiles such as laboratory attire, the contents of natural history-type collections gathered by the 19th and early 20th century professors of botany, biology, histology or anatomy, or even collections of scientific data on slide film or videotape are a few examples.

Ultimately, one must reconcile competing goals and priorities. Coherence could be an important characteristic of a research collection. On the other hand, it would be unfortunate to ignore the broader material history of science beyond the limits of scientific instruments. In this sense, the psychological tests serve as a reminder of the ways in which scientific projects, and their relationship to cultural movements, may be studied a diverse range of material objects.

Thank you to the Friends of the CAMH archive for supporting this ongoing research.

Having finished the glass microsyringes needed to restore a historical Chambers’ micromanipulator to working condition, the one piece of glassware remaining to be made is the glass chamber. As discussed in the previous post, a glass chamber is a kind of clear cage that sits on the microscope stage. When used with a standard microscope, the sample is contained in a drop of liquid suspended from a large cover slip that forms the roof of the chamber. The observer looks downward through the flat surface of the coverslip into the droplet. The chamber, which can be sealed, creates a microenvironment that slows the evaporation of liquid from the sample. It also provides a space for the tool tips of a micromanipulator to operate upward into the sample contained in the liquid drop.

An illustration of the glass chamber along with a view of the photograph of the chamber in place on the microscope stage. [Chambers 1929, 63)

I haven’t discovered what sort of chamber was used with the Chambers’ Micromanipulator that was purchased by the University of Toronto’s School of Hygiene in the late 1920s. Assuming that only one kind was used, it could have been a factory-made version ordered from the Leitz company, or a different design than the one that I made. It’s quite likely, though, that its users would have paid a glassworker to construct a type repeatedly described in the published work of Robert Chambers, inventor of the Chambers’ Micromanipulator, as well as in trade literature related to the instrument and other sources. Instructions for making it can be considered standard—Chambers and his collaborators did much of the early writing about micrurgy. [Chambers (1922a), 340; E. Leitz, Inc. (1926), 10; Chambers and Kopac, (1950), 311]

A homemade glass chamber. As a recreation it is functional and cosmetically OK.

The glass chamber described in these early sources was relatively straightforward. It consisted of a “fairly thin” glass base of about 50 x 70 mm on which the glass chamber was built. The chamber walls were made from strips of float glass or bakelite, an early plastic. It was roofed over by a large (22 x 40 mm) coverslip.

Remaking the chamber

I followed Chambers’ design as closely as possible using the most affordable material that I could find: thin (1.7 mm) soda-lime float glass cut from the glazing found in cheap picture frames from the dollar store. The entire chamber is made from this glass except for the two top support pieces (A), cut from the slightly thinner glass of a microscope slide, and the coverslip which I purchased online from a laboratory supply site.

An exploded view of the chamber as I made it, drawn in SketchUp.

I cut the glass using a basic glass cutter from a hardware store. This is a pen-like tool tipped with a small wheel that tapers to a narrow edge. When drawn along a piece of glass, the wheel produces a score line. When pressure is applied to the scored glass, it will tend to split along this line. In practice, this isn’t easy to do reliably when making long, narrow pieces such as those used in the walls of the chamber. A higher quality tool with a tungsten carbide cutting wheel rather than a steel one would probably make this easier.

A setup for cutting glass in a reasonably precise way. Repeated cuts can be measured using a paper template. Pieces of duct tape provide a bit of friction to keep the glass in place. Using a cork-lined ruler also helps to keep the cut straight. The cutter is lubricated with oil before the score line is made. Pressing the surface opposite the score line against a raised a narrow object like this metal tube helps to start the crack.

The limits of recreation

When I recreated the glass micropipettes that would have been used with this chamber, I felt able to explore some of the “gestural” techniques that the instrument’s operators would have had to master. This wasn’t possible when making the glass chamber. Having spoken to the one remaining scientific glassblower on the U of T campus, whose colleagues know the history of the trade, I learned that in the 1920s or 30s, the parts of the chamber would originaly have been made with a specialized saw used to cold work glass and ceramic.

The glass cutter method is a cheap and rather inefficient compromise. I found it easiest to cut many pieces and select the best. While a diamond saw blade will leave a relatively clean edge, the crack that propagates from the scored line created by a glass cutter leaves an uneven cut surface. For cosmetic reasons, I tried to even this using a diamond file, though even very rough surfaces would have had no impact on the chamber’s usability. The best option, of course, would be to commission the pieces from a glass worker with the proper tools.

With any such recreation project, one could get deeply into minutia. Much of the interest comes in setting arbitrary boundaries around what aspects of a historical object to attempt to recreate and what to ignore. It may be worth mentioning, for instance, that the historical directions suggest gluing the pieces together with Canada balsam, a natural material made with the resin of the balsam fir tree. I used modern 2-part epoxy since no glued surface is actually in the optical path.

There are also some potential considerations regarding the height of the chamber. When working with high magnification, this measurement needs to be carefully matched to the focal point of a modified microscope condenser. This is so that high magnification objective lenses receive enough light since they are operating at a greater distance from the microscope stage than if they were used with a standard slide. For my purpose, a chamber within the ballpark range of 8 -10mm is sufficient since I will not be working with especially powerful objectives.

All in all, I’m satisfied with the finished chamber. I expect that it will work well for its intended purpose: the eventual dissection and injection of a living amoeba. It also looks convincingly like the examples shown in a few surviving photos, especially from the distances at which one would normally observe a reproduction in a museum exhibit.

In the next post on this topic, I’ll discuss the development of microinjection systems used to inject tiny amounts of liquid into living cells or to gather individual microorganisms. The microinjection apparatus is missing from the U of T Chamber’s micromanipulator and I have also attempted to recreate it.

The development of the “hanging droplet method” was a crucial step towards establishing the micromanipulator as a useful tool with which to study the living cell. Developed around 1904 by Marshall A. Barber, a professor of bacteriology at the University of Kansas, this method involved placing a sample in a droplet of liquid (usually water) adhering to the bottom surface of a large cover slip that formed the roof of a glass chamber.

This “moist chamber” was placed on the microscope stage such that the user observed the sample in the droplet through the flat surface of the cover slip. The chamber was open on at least one end to permit the entry of microtools whose tips operated upward into the droplet. While these tool tips could be moved independently relative to the sample using a micromanipulator, the sample itself could be moved relative to the tips by clasping the chamber in a mechanical stage as shown in the photo below.

A glass chamber in place on a microscope stage with microtools (one microscalpel, one microsyringe) extending into it. The chamber is held in a mechanical stage which can position it along the x and y axes. The micromanipulator mechanisms can move the microtools along three axes relative to the chamber. In this case, the microscope incorporates a microscope stage that can be rotated. [Chambers 1929, 63]

In this illustration, a hooked microscalpel is used to cut through the soft membrane of a sea-urchin egg. The surface tension of the droplet is firm enough to hold the egg in place as the scalpel is drawn downward through it. [Chambers 1921b, 327.]

While a droplet of liquid might seem a weak enclosure, it could usefully hold a variety of microscopic objects. Individual bacteria or other microorganisms could be recovered from droplets of growth medium adhering to the cover glass. Larger microorganisms, such as amoebas or paramecia, could be caged within a liquid droplet for the purpose of vivisection or the injection of colour indicating dyes to study cell metabolism. Fresh tissues and cell samples could also be studied in this way.

The hanging droplet method addressed several problems with previous methods. The glass enclosure provided a moist atmosphere that prevented the liquid from evaporating. This was maintained by pooling water in a shallow well on the floor of the chamber or by lining its sides with damp blotting paper. The sample could be preserved in the chamber by closing the open end around the shafts of the microtools. A simple seal could be made using a cardboard frame containing cotton fibres and Vaseline. [Chambers and Kopac 1950, 511-512]

An inverted microscope developed for use with the Chambers’ micromanipulator. It would be interesting to discover exactly what role the hanging droplet method played in the development of the inverted microscope.

Whereas earlier methods had required the observer to look through the meniscus of a pool of liquid, which introduced optical distortions when the tool tips entered the liquid, the hanging droplet method placed the sample beneath the flat surface of a cover slip. In addition, previous methods had placed the microtool tips between the microscope objective and the sample. When the tools were located beneath the droplet, the microscope objective could be moved closer to the sample. This made room for more powerful objectives with shorter focal lengths.

The system was easier to use with an inverted microscope. One such instrument was developed by the Leitz company for the highly-effective Chambers’ micromanipulator in 1933. In this case, the droplet sat on the floor of the chamber and the position of the tools and objective were reversed.

Evolution and elaboration

From the invention of the hanging droplet technique in 1904 to the mid-to-late nineteen thirties, when the technique had become widely used, the technology evolved considerably. The chamber was initially made locally, most likely by laboratory glass blowers. As it was relatively easy to make, this practice no doubt continued—instructions for making it were provided in the 1950s and possibly later as well. [Chambers and Kopac 1950, 511-512]

Moist chambers did become available commercially, notably a version—again manufactured by Leitz—that was used with a dark field condenser created specifically for micrurgical work. Other specialized equipment such as an electrically heated jacket for the chamber was devised by researchers. [Howland and Belkin 1931, 16-18]

As the system began to reach its potential, shorter chambers were used. This is because the height of the chamber was determined by two factors: the need to manoeuvre the delicate glass tool tips within the glass enclosure without breaking them, and the need to properly illuminate the sample using the microscope condenser.

The microscope condenser is an optical system located beneath the microscope stage that focuses light onto the sample. Since samples are usually placed on glass slides between 1 – 1.2mm thick, standard microscope condensers are designed to focus light within a narrow range just above the microscope stage.

A particularly tall moist chamber set up for isolating bacteria. The cross marked on the cover glass is to help orient the user to the location of bacteria colonies. [Kahn 1922, 346]

The hanging droplet method located the sample substantially beyond the normal operating range of the unmodified microscope condenser. This was not a problem initially since the hanging droplet method was first used to isolate microorganisms, a process that did not require especially high magnification. This type of operation would always use a larger chamber for convenience since it involved the frequent removal and reinsertion of micropipettes into the chamber in order to gather multiple samples.

As the micromanipulator was increasingly used with more powerful objectives to discern the structures within living cells, stouter chambers were required in order to achieve proper illumination from the condenser. This also required condensers that could focus light well above the microscope stage. Specialized condensers were sold for this purpose, though many conventional research microscopes featured condensers that could be easily modified. [Chambers 1922a, 339-340]

Sealing the chamber, isolating the droplet

The hanging droplet method, as originally devised, had several limitations. Beyond the difficulty of illuminating the sample, the open enclosure, heated unevenly by the microscope illuminator, permitted moisture to evaporate from the droplet and recondense on the walls of the chamber. [Fonbrune 1949, 130]

The “oil chamber” (chambre à huile), developed in the early 1930s by French researchers Pierre de Fonbrune (1901-1963) and Jean Comandon at the Pasteur Institute, addressed a number of these limitations. [Fonbrune 1949, 130-131] This was a very shallow chamber (1-3 mm high) open at both ends.

Biological investigation in the oil chamber could involve blood, living tissue or microorganisms. In the upper two photos, a nematode caught in the ring-shaped traps of the carnivorous Dactylaria brochopaga fungus. The bottom two photos show a trap, open in the first photo, closed in the second after having been touched by the tip of a microneedle. [Fonbrune 1949, 138]

The sample in an oil chamber was contained, as before, in a liquid droplet suspended from a coverslip. However, this droplet was surrounded by paraffin oil which effectively created a microenvironment isolated from the atmosphere. The shallow space between the coverslip and the glass floor held the oil in place by capillary action. This prevented the loss of moisture to the atmosphere and increased the survival time of living samples .

The oil chamber was likely made possible by developments in the technology of micrurgy that had accrued by the 1930. This would have included instruments for making microtools that made it possible to produce the very short tool tips necessary to operate within the confines of the shallow oil chamber.

There were other reasons for sealing the chamber. Over the mid 1920s, Cambridge biologists Joseph (1900-1995) and Dorothy Needham (1896-1987) experimented on cell metabolism using a modified Chambers’ micromanipulator. Some of these chemical operations—for instance those involving anaerobic bacteria or the injection of highly reduced dyes for testing the oxidation potential of microorganisms—required an anaerobic environment within the chamber. This was achieved by passing the the microneedles through a shallow trough of mercury while the chamber was filled with a stream of nitrogen. This anaerobic chamber—notably the bent needle and mercury trough arrangement—was first suggested by Marshall A. Barber in 1918 but it was the Needhams who first explored it. [Needham and Needham 1926, 385]

Needham and Needham’s anaerobic chamber. Specially formed glass microneedles (L) pass into the chamber through a trough of mercury (G). Nitrogen flows through the chamber, entering through tube D and exiting through C. The chamber is roofed over by a large cover slip (R) to which a smaller “flying” cover slip adheres by a film of water. The drop (T) is suspended from this second cover slip. [Needham and Needham 1926 , 386]

As a laboratory technology, the hanging droplet technique was highly adaptable and hence widely adopted. It is still in use. One also finds variations of this technique beyond the biological realm, for instance in chemistry where the moist chamber provided a kind of miniature laboratory bench upon which capillary vessels were used to perform experiments at the microgram and nanogram level.

(Left) Top and side view of a moist chamber used in chemical experiments that was developed in the early 1950s. The chamber dimensions are around 6 x 6 cm. (Right) A simple rack and pinion micromanipulator holding a micrometer syringe for use in chemical operations. [El Badry 1963, 102]

At an event celebrating the opening of a new University of Toronto physics building in 1907, University President James Loudon (1841-1916) described the challenges that he had faced in setting up the University’s first physics laboratory in the late 1870s. Among other topics, he spoke about the importance of craft skills to furnishing basic laboratory apparatus.

In one of my first difficulties—how to make air-tight joints between glass and iron tubes—I applied to the late Professor Rowland, of Baltimore, and received the advice to break a dozen tubes in discovering a way. To learn by making mistakes is not a bad plan, if you can afford it. [Loudon 1907, 45]

Loudon’s anecdote exposes a facet of scientific practice that we don’t often consider. Certain laboratory tasks require researchers to master difficult manual skills. This poses a challenge to scientific communication because such tasks (as implied in the advice given to Loudon) are difficult to teach and to learn. We can explore these processes by “re-enacting” or “recreating” them—an approach that has been developed by historians of science to expose those elements of an experiment that remain unreported.

For the past year or so, I have been studying the process of making glass micropipettes that, beginning in the first decades of the twentieth century, have been used to inject material into, or remove material from, individual cells. This is part of a bigger project to remake various missing parts from a Chambers’ Micromanipulator that was acquired by the University of Toronto in the late 1920s or early 1930s. The experience of remaking these delicate glass objects could be taken as an example of how we might study the craft-like laboratory skills that used to (and still do) underlie various aspects of scientific research, especially in the early stages of a technology’s development before novel tasks are automated and become “black boxed.”

The Task

The type of glass microsyringe that I am seeking to recreate would have been mounted in a microinjection apparatus used with a Chamber’s micromanipulator. This system is depicted here with the glass microsyringe (circled in green) mounted in the removable tip of a tool holder.

By the late 1920s, nearly every part needed to operate a micromanipulator could be purchased from a Leitz catalogue. Glass microsyringes were an exception because they were very fragile, easily clogged, and had to be clean and sterile. They were considered disposable and were typically made just before they were used.

As these tools became common in medical and biological research laboratories over the first half of the twentieth century, many researchers gave their own instructions for making them when describing the apparatus used in their experiments. The illustrations on the right accompany a particularly detailed set of instructions given by Robert Chambers (1881-1957) , inventor of the Chambers’ micromanipulator and, for decades, the most prominent researcher in the field of micrurgy.

As noted earlier, this process involves softening a glass tube of 3-5mm in diameter in the flame of a Bunsen burner and pulling it into a capillary of between .5 and .85 mm in diameter. This step is not shown here, probably because the instrument’s users would have known how to “pull pipettes”.

The photos show the making of a tool tip using the pinhead-sized flame of a microburner to soften a section of this capillary while applying tension to both sides of the tube. Done properly, the capillary separates into tapering tips. The base of the tip is then bent upwards in the heat of the microburner flame and the finished micropipette is stored for later use. When needed, the capillary is shortened to about 5cm and placed in a tool holder to be mounted in the micromanipulator.

Chambers’ description of the critical moment in which the tip is made conveys the challenge of this process:

The capillary will separate with a slight tug—a feeling much like that experienced when a taught thread, held in the fingers, is parted in a small flame… Everything depends upon the amount of heat used and the timing of the added pull, and these vary slightly with the height of the flame and the diameter of the capillary. With a little experience, one can usually tell when a proper tip is made by the peculiar feeling just described. [Chambers 1951, 81]

Even when successful, certain tips were more suitable to a particular research task than others. Inspection under a microscope would reveal exactly what kind of tip had been created. Both the challenge and the variability of this process led researchers to develop instruments to automate and regulate it.

Homemade glass tool tips under magnification. The broken tip on the left has been smeared with blood. Red blood cells (~6–8 μm) adhering to the walls give a sense of scale. The image on the right shows an unbroken tip at the same level of magnification. In his early experiments, cytologist Robert Chambers noted that it was not unusual to produce tips of half a micron in diameter using Jena glass, an early borosilicate glass. [Kite and Chambers 1912, 564]

Remaking: setup and supplies

Historians usually take on these sorts of projects with help from museum conservation departments, university technicians, or backing from other well-funded institutions. For various reasons, my work with the Chamber’s micromanipulator is both and academic collaboration and a DIY project. While I have had generous help on various aspects of the project from the machine shop at the U of T Department of Physics and the Semaphore maker lab at the Department of Information Studies, I have made the glassware on my own.

The most basic laboratory glasswork requires a supply of natural gas. (Serious laboratory glasswork, generally done by professional glassblowers, requires both compressed propane and oxygen.) Since working scientists tend avoid letting historians play with fire in their laboratories, I have had to improvise. The straight forward solution would have been to purchase a Bunsen burner, a small propane cylinder, a low pressure gas regulator, and a length of rubber tubing. I settled on a cheaper solution: a $7 camping stove that mounts on a $5 bottle of propane/ butane camping fuel. With a small central burner, this stove is very serviceable for softening a Pyrex pipette, though probably less efficient than a stove with a wider ring-shaped burner for heating food in the wilderness.

The photo on the left shows the tools and materials used for making glass microtools c. 1950. [Chambers 1950, 514] On the right are my own equivalents. The relatively short 9 cm tubes that I use are best gripped by pliers when pulled into pipettes in the heat of the camp stove Bunsen burner. The short sections remaining on either end can be re-pulled using this method.

The microburner was more of a challenge. Historically, this was usually just a narrowed piece of hard glass or a hypodermic needles attached to a gas supply with a rubber tube. The gas was regulated by placing a pinch valve over the tube. After some tinkering, I ended up with a wooden mount for a Bic lighter. The mount features a swiveling arm that can depress the valve just enough to produce a tiny flame.

I was very lucky in my search for suitable glass tubing. Active Surplus, a maker’s paradise in downtown Toronto, sells surplus capillary tubing of roughly the right size. At 2.9mm in diameter, these are very close to Chambers’ recommended range of 3 – 5mm. At 50 cents for a tube 9.5cm long, this was much cheaper than ordering from an online supplier.

Scientific glassware at Active Surplus in Downtown Toronto. This is a great place to look if you’re starting a DIY project.

Playing with fire

Using this equipment, I was able to follow the Chambers’ instructions for making micropipettes. I found the process of producing the finished tip to be just as finicky a Chambers described, though the process of consistently pulling the 2.9 mm tubes into capillaries of .5 – .9mm in diameter and 5.5 – 8cm in length was much harder than I expected. The final step of bending the tip is especially frustrating because it is very easy to melt the tip itself.

A number of consecutive attempts at drawing out glass tubes into capillaries. Several are too short. A number are slightly too thin—a consequence, no doubt, of starting with tube slightly narrower than the recommended range.

There are several factors that need to be balanced throughout: the intensity of the heat source, the amount of material to be heated, and the degree of softness that the material reaches. It is easy to overheat the glass and produce a long flexible filament.

Making these tools reminded me of the frustrating process of learning to serve a squash ball. In both cases, I found myself trying to reason my way through by constantly adjusting my approach, but to no real effect. The advice to “break a dozen tubes in discovering a way”—akin to “keep playing squash until you can serve the ball”—seems to apply.

Finished glass micropipettes ready to be trimmed and mounted into a microinjection apparatus. Strips of fine corrugated cardboard that have been laminated together work well as a holder for the fine pipettes. A flip-top box forms an enclosure that is less likely to damage the tips.

Craft skill and “gestural knowledge”

In studying the production of scientific knowledge, historians have begun to notice the “non-verbal, non-articulate and preconceptual elements of experimental activity.” [Voskulh 1997, 338] This emphasises the role of the experimenter’s skill in a process that tends to be conveyed, whether through text or demonstration, in such a way as to stress the self-evidence of a particular finding. A masterful article from 1995 by Hanz Otto Sibum introduced the notion of “gestural knowledge” to encompass the “complex of skills and forms of mastery” necessary to produce an experimental effect, though he also applied the term to craft skills more generally. These two senses intersect in his exploration of James Prescott Joule’s (1818-1889) experiments on the mechanical equivalent of heat. [Sibum 1995, 73-74]

Sibum interpreted Joule’s skill with the thermometer against the backdrop of the Manchester brewing industry of the mid-19th century where practical, imitative knowledge was being supplanted by the highly precise methods of practical chemists. Joule, the son of prosperous brewers, depended on this tradition of monitoring the brewing process using thermometers for his success as an experimenter. Sibum’s insight came, in part, from his own attempt to re-enact Joule’s experiments using recreated apparatus. [Sibum 1995, 83-95]

The process of making glass microtools is, in certain respects, similar to the traditional skills of the malsters and brewers or Joule’s modern skill with the thermometer. All are forms of manual mastery obtained through experience. All represent the intersection of craft skills with laboratory research.

These examples differ, perhaps, in the sense that historians of science tend to invoke craft skill in search of the hidden and implicit within an experimental account—Sibum’s re-enactment of Joule’s experiment demonstrated the care and skill needed to obtain precise results. Rather than eliding the difficulty of a scientific operation, Chamber’s instructions are explicit about the manual challenges involved. Tracing similar instructions for making glass microtools over the history of micrurgy, one sees them becoming more detailed with time as the difficulty of the gestural knowledge required for the task became more evident among a widening pool of new users.

In fact, it is a bit misleading to compare this rudimentary laboratory process with the sorts of experimental claims that historians have tended to study through re-enactment. For this reason, I’ve come to prefer the term “tactile history of science” to others such as “experimental re-enactment” or “scientific recreation” because it broadens the scope of the remaking/ re-enactment process beyond the experimental report to include the everyday operations of laboratory work. I’m not sure where the term “tactile history of science” originated, but I encountered it on Will Thomas’s blog, Ether Wave Propaganda, where you can find a good explanation and an excellent series of posts on the topic. Compared to terms that emphasize experimental claims, I think that it gives historians a broader mandate to study the scientific researcher as a maker while giving makers an entrypoint into the history of science.

Using simple tools, a fine glass tube (capillary) can be drawn to a point fine enough to dissect a single red blood cell—an object about 6-8 μm (6-8 thousandths of a millimeter). The capillary’s interior channel will diminish in proportion to the walls. By removing the very tip, a syringe is made that is fine enough to inject material into, or remove material from, individual living cells. While other materials can produce tool tips of microscopic fineness, none combine the workability and chemical neutrality of glass.

Microsurgery using glass tools: In the top photo, the amoeba on the right has had its nucleus removed; the one on the left is healthy. In the middle photo, the nucleus is removed from the healthy amoeba and placed in the previously denucleated one. The bottom photo shows amoeba on the right having recovered its cellular activity a few minutes later. The second photo shows two glass microtools, a microneedle and a “crochet-butoir” (a “hook/ stop”), made using De Fonbrune’s microforge (see below). The white circle in the top corner of each image is a clock superimposed on the photo. [De Fonbrune 1949, 174-175]

Of course, other instruments are needed to mount these glass tools, to manoeuver them in space, to contain the sample, and observe the process. This apparatus centers on the microscope and micromanipulator. In the late 19th and early 20th centuries when the technology of micromanipulation (referred to more succinctly as ‘micrurgy’) was being developed, all of this equipment could be purchased commercially or manufactured in local workshops except for the glass microtools which are too delicate and disposable to be made outside the lab. Making useable tools in sufficient quantity took a great deal of practice.

Here I want to trace the various early methods for making glass microtools that were described by the people who first developed them. Because the process was inherently difficult, investigators created new instruments to make this process more reliable while also making possible more specialized and elaborate microtools.

How to make a micropipette

Begin with a glass tube of about 3-5mm in diameter. (Solid rods can be used as well, but are only useful for dissection.) This can be made either of “soft” (soda-lime) or “hard” (borosilicate) glass. Hard glass is more durable and alkali free but is also harder to work because it softens at a higher temperature. Soft glass can be drawn into a slightly finer point. Heat the tube in a Bunsen flame and when the heated section becomes soft, pull on both ends to draw it into a narrow pipette between 0.3 – 0.8 mm in diameter. (These measurements vary somewhat depending on the source.) Then use a much smaller heat source to pull a finished tip on this pipette.

Tool tips depicted in an article by Barber in 1911. Further, more detailed, illustrations were later published by Robert Chambers. [Barber 1911, 351]

This tip is especially difficult to make because of the relatively small amount of heat necessary to soften the fine pipette and the challenge of pulling it in such a way as to produce a tip that is sturdy and straight. It is very easy to apply too much heat resulting in a fine, flexible “hair” (think of a fibre optic cable), or to end up with a bent, broken, or poorly centered tip. Certain tip profiles are best suited to certain kinds of work. The variability involved in making these tools by hand typically meany that one would produce a number of them, then sort them according to their profiles.
There are various ways to make these tips, each of which comes with its own complications. The simplest and earliest was described by the French biologist Laurent Chabry (1855-1893) in a paper published in 1887. Chabry’s method involved placing the fine glass filament against an incandescent object (for instance a heated bead of glass) and then withdrawing it quickly. This method was very imprecise, however. In a morning’s work one could only expect to make four or five serviceable points. [Chabry 1887, 176]

A second method was introduced by Marshall A. Barber, a professor of bacteriology at the University of Kansas. This involved a microburner—an improvised device that attached to the laboratory gas supply which could produce a useful flame of about 2mm. This tiny heat source can be used to soften the glass of the filament just enough that it can be pulled apart by hand with both separated halves tapering to a fine tip.

Barber published an article in 1914 that included an illustration of the microburner which would be borrowed and republished for more than thirty years:

The microburner was far from a perfect tool. In 1932, J. Arthur Reyniers, a bacteriologist at the University of Notre Dame, stated bluntly that “Gas micro-flames are useless in this work because they cannot be accurately regulated.” [Reyniers 1933, 271] Reyniers was among several researchers who developed new instruments to produce these essential glass tools more easily and reliably.

Mechanizing the process

Efforts to make it easier to create glass microtools began very early in the development of micrurgy. Chabry developed a system that involved sliding the glass pipette along a grooved surface. By sliding the pipette into contact with the incandescent platinum blade of an instrument used for cautery, then quickly withdrawing it, he was able to produce straight tool tips with reasonable consistency. [Chabry 1887, 177]

A new series of pipette-making instruments emerged from a 1908 invention by Keith Lucas, a Fellow at Trinity College, Cambridge, who worked in the physiological laboratory. Lucas’s instrument used a loop of electrified platinum wire that encircled the central part of the pipette to be softened. The pipette was clamped on both ends and under tension. Because both heat and tension could be regulated precisely, this technology made it possible to repeatedly produce good tips and even to precisely create tips of a particular kind. [Lucas 1908, xxviii-xxx]

A number of instruments were developed based on Lucas’s method. A simple, compact device, developed in 1931 by Delafield Du Bois of New York University, was distributed by the Leitz company over a long period. Today, sophisticated programmable machines such as the MicroData Instrument PMP series will produce a variety of tips to very precise specifications.

There is more to this story than the familiar mechanization of a skill-intensive laboratory process. Glass micropipettes were simply the most basic and adaptable of an ever-growing family of purpose-built microtools ranging from microelectrodes, to tiny crucibles used in chemical operations, to elaborate apparatus meant, for instance, to measure pressure in the smallest capillaries. (A number of these are described in this digitized source.) Fabricating these instruments would typically have required the skills of a laboratory machinist and/or glass blower.

Tool tips created with De Fonbrune’s microforge. The scale is in hundredths of a millimeter. [Fonbrune 1949, 22]

At least one tool did emerge that expanded the researcher’s ability to make glass tools. The “microforge” was introduced in 1937 by Pierre de Fonbrune (1901-1962), Chef de Laboratoire at the Pasteur Institute in Paris. It provided a means to make elaborate tool tips that would have been impossible using earlier techniques.

Like the common forge, the microforge was a craftsperson’s tool, permitting the user to apply heat and pressure to shape glass at a microscopic level. Heat was again provided by an incandescent wire. Pressure came from jets of air. Both could be positioned relative to the glass workpiece. Work was done under magnification. De Fonbrune, provided detailed instructions for making various tools. Modern versions of this instrument are still being made.

In this very brief survey, I don’t want to suggest that there are no similarities between laboratory work and craft work and that the making of glass microtools represents some kind of unlikely exception. On the contrary, many historians and STS scholars have pointed to the importance of manual skills in the production of scientific facts.

Reading the instructions left by early experts in the field, though, I’m struck by the extent to which the process of making glass instruments depends on mastering complex and intuitive manual skills through practice. This certainly isn’t the case with all experimental labour. In my next post, I will explore this process of bodily (or ‘gestural’) knowledge by discussing the experience of making my own glass micropipettes.

The availability of historical microscopes in the UTSIC collection makes it feasible to operate the U of T Chambers’ micromanipulator somewhat like it was operated by its original users in the late 1920s and early 1930s. Of the various possible uses to explore, the dissection of larger single celled organisms such as the amoeba seems most practical. Such scientific recreations (some have called this process experimental reenactment, “reperformance”, or reworking) have become increasingly common in the humanities, and particularly the history of science, not least because they can be engaging, vivid, and memorable.

In 2009, I saw a very impressive recreation of Heirich Hertz’s 1879 experiment which demonstrated the existence of electromagnetic waves. Historian Roland Wittje used a rather terrifying historical spark gap transmitter to generate radio waves (“anyone here have a pacemaker?”). When a separate receiver—a simple antenna consisting of a loop of copper wire with a small spark gap—was moved to a place in the room that corresponded to a standing wave, a tiny spark appeared within the gap in the antenna.

Another impressive demonstration: in 2005, historian Peter Heering, used materials and expertise of the Deutches Museum in Munich to demonstrate the use of the solar microscope, eighteenth-century demonstration instrument that used the light of the sun to project an image from a prepared microscope slide into a darkened room. The instrument created a large and intense image, especially when newly prepared slides were used (the originals had deteriorated with time). Wittje and Heering are members of a movement that explores the history of science by seeking to recover the scientific experiences of the past.

“Projection of a flea (modern preparation with drying and embedding) with Dollond’s solar microscope for an audience”. An illustration accompanying Heering’s 2008 article in BSHS.

What can recreations tell us?

Historians of science and other academics make a variety of claims about the meaning and value of recreating past technologies and practices. One is the notion that this process allows us to fill in gaps in the textual or material record–to rediscover what has been forgotten. Most obvious are cases in which no written records exist at all. Often, in order to develop a plausible theory explaining an artefact from a vanished, non-literate human culture, archaeologists study how it was made and its practical value as a tool—experimental archaeology is the name given to recreations meant to assist this research. The famous Bâton de Commandement, a bone tool, could be ceremonial object, a spear thrower, a calendar, or a spear straightener depending on which interpretation seems most convincing to you.

Touching the history of science, recreations have been used by historians of alchemy, who study a set of practices for which textual accounts about materials and practices do exist, but whose public discourse took place in a pre-modern idiom meant only for a small community of well-studied philosophers. Modern chemical materials rarely correspond to the materials that were in use before the emergence of current chemical methodology. Historians of chemistry, including Lawrence Principe and Jennifer Rampling, use experimental recreation as one means to decode these materials and practices in order to reproduce effects reported in early modern sources. For instance, Principe reproduced a “Philosopher’s Tree”, a key point in an early modern alchemical recipe for transmuting base metal into gold, using the the laboratory notebooks, correspondence, and published texts of the 17th-century alchemist, George Starkey (1628-1665). Principe describes this experiment in his excellent book, The Secrets of Alchemy(2013, p. 165):

Following Starkey’s hints, I mixed this Mercury [i.e. a specially prepared “animated” Philosophical Mercury] with gold to produce a buttery mixture, which I placed in a flask approximating the form of the philosophical egg. The “egg” was sealed, buried in a sand bath, and heated. For several weeks, I varied the heat, since the original texts did not (and in fact could not, in the age before laboratory thermometers) provide a clear indication of the temperature used originally. The mixture did little more during this time than swell slightly, increasing in fluidity and then becoming partly covered in warty excrescences. Finally, a few days after the right temperature had apparently been achieved, I arrived at the laboratory one morning to discover that the mixture had taken on a completely new—and extraordinarily surprising—appearance overnight. Only a gray amorphous mass lay at the bottom of the flask the day before, while a grey and fully formed tree filled the vessel on the following morning.

Close-up photograph of a “Philosopher’s Tree” produced by Principe in his laboratory. This image is a scanned copy of Plate 6 in his book “The Secrets of Alchemy.”

Even in the case of relatively modern, well-documented technologies, recreations can resolve ambiguities and controversies in surviving textual accounts. Heerings account of the solar microscope, for instance, was inspired by the difficulty in reconciling the claims of its makers, which appeared mainly in advertising copy, and its nineteenth-century detractors, who typically regarded it as a toy and who may have known only inferior instruments. Heering’s recreation showed that well-made instruments and skilled demonstrators could use the instrument to produce remarkable effects during a period when scientific practice enjoyed great popularity, and was often pursued and discussed in a sociable atmosphere.

Some historians also maintain that such recreations can recover aspects of experimental practice that rarely appear in published accounts. In an article in 1995, historian Heinz Otto Sibum discussed his recreation of a 19th century experiment by James Prescott Joule (1818-1889) that demonstrated the transformation of kinetic energy into heat. Joule’s experiment relied on a weight-driven paddle wheel mechanism operating in a vat of water whose operation would generate heat from friction which could then be measured with a thermometer. Sibum’s efforts to reproduce this remarkably complicated experiment brought him to the concept of “gestural knowledge” which describes the “complex of skills and forms of mastery” needed to successfully produce an experimental result. From this perspective, recreation (Sibum called it “reworking”) offers a way into the network of circumstances involved in the creation of a scientific fact—Sibum identifies the importance of the Manchester brewing tradition, a source of the gestural knowledge needed to maintain the consistency and quality of a brew, as the basis of Joule’s skill as an experimenter. I will describe a more modest example gestural knowledge in my next post describing the process of recreating glass microtools necessary to use the Chambers’ micromanipulator.

Defining a project

It should be possible to put the Chambers’ micromanipulator into working order using existing equipment in the University of Toronto collection. This can be done without risking damage to a historical instrument that may well be unique. The instruments versatility offers a number possibilities, though other factors limit them. Of these, the availability of historical microscopes is the greatest limiting factor. Serious critical work, such as might have been done on bacteria at the University of Toronto School of Hygiene, requires powerful microscope objectives, often with matching oculars, which (for reasons that I’ll discuss in a future post), aren’t well represented in the UTSIC collection. Some equipment such as darkfield condensers and binocular microscopes (the School of Hygiene apparently used Zeiss binocular microscopes in the late 1920s) are missing entirely.

Fortunately, in 1931, Chambers’ colleagues at New York University (to which he had transferred from Cornell in 1928) produced a manual that was meant to be used to train students on the instrument. The “Manual of Micrurgy” has been digitized and is available for download from the Internet Archive. It outlines several preliminary exercises involving the dissection or injection of larger cells and living microorganisms (amoeba proteus, amoeba dubia, aciliophoran, human cheek cell). These practice experiments were meant to familiarize students with the instrument’s controls.

All of these cells are relatively easy to obtain and are visible under moderate magnification. This is important since, as an amateur microscopist, I’m less comfortable working with very high power objectives which are more prone to accidental damage as they operate very close to the focal point and typically require the addition of immersion oil or water to period optics. These training exercises seem like a reasonable goal in a project aimed at recreating the instrument.

The Manual of Micrurgy was produced by the faculty of the New York University Department of Biology several years after Robert Chambers, inventor of the Chambers’ Micromanipulator, was recruited from Cornell. This digitized copy is from the Marine Biological Laboratory in Woods Hole where Chambers was then doing research.

The limits of recreation

Like any account of history, recreations are fundamentally acts of interpretation and translation which are bounded by the interests, abilities, and resources of the interpreter. Neither the yellowed eighteenth century microscope slides of the solar microscopes studied by Heering nor the clearer modern versions using present day materials could perfectly represent what eighteenth-century audiences witnessed in their well-furnished salons. Likewise, every aspect of a recreation involving the manipulator, from the modern tungsten light bulb in the recreated microscope illuminator, to the epoxy glue binding the glassware, to the CCD used to create images through the microscope, represents a compromise.

Even if we could somehow make our recreations perfect, past experience and knowledge would remain elusive. The historian of chemistry might recreate the authentic materials used by early modern alchemists—ambiguous and impure by the standards of modern chemistry—but she can never rid herself or her readers of an awareness of those modern standards.

A passage written by historian Adelheid Voskuhl conveys the value of this form or research. In recounting her efforts to operate a recreation of John Herschel’s (1792-1871) actinometer, an instrument for measuring the intensity of solar radiation, Voskuhl describes recreation (she calls it performance) as a means “to shift the historical object-of-research away from the document or the performance itself towards an interpretation of textual and non-textual sources that has its foundation in the analysis of a historical context where documents and practices come into being.” I take this to imply, in part, that recreation provides new ways of exploring existing evidence because it requires you to ask questions of your sources that other approaches do not. I hope that the process of setting up and using this historical instrument, which I will describe in future posts, provides some good examples of this.

Thanks to Gwyndaf Garbutt for helping me wrap my head around this topic.

In the summer of 2009, I took part in a workshop at the Canada Science and Technology Museum (CSTM) during which we were shown a number of objects from their collection. One was a console from a SAGE computer system, once used by NORAD to detect and track soviet aircraft entering Canadian airspace over the arctic. This is an important object representing a significant application of early computers, as well as Canada’s early Cold War status as an enormous frontier in which to prevent Soviet bombers from reaching the United States. David Pantalony, Curator of Science and Medicine, pointed out ashtrays that had been built into the console. He also noted that, when the object was first acquired in the 1980s, there were cigarette stains visible on its surface—a trace of the operators whose job combined tedium and incredible responsibility. Since its acquisition, however, the object had been cleaned, the traces of its human operators removed.

It could be that no object is ever complete. No matter what you feel that you know about it, some aspect of its meaning will escape you. Whatever interpretation you give it, or how you choose to represent it, some other narrative will be obscured or distorted by your claims. Curators, like historians, are essentially storytellers. The act of discussing the past involves selecting certain details over others, deciding which voices are too peripheral to matter, reconciling conflicting views according to your own weighing of the evidence. Both curators and historians tell stories that adhere to professional conventions meant to make this process of weighing seem fair and reasonable. Conventions change over time. One generation of curators might restore a given object to match an ideal form that existed when it was new, another might find significance in its brokenness or incompleteness.

A control stand from an Victor “Snook Special” x-ray machine. It was purchased in 1926 for the University of Toronto physics laboratory run by John Cunningham McLennan (1867-1935). On the left is part of the schematic that was sent with the original unit. On the right is the unit as it appeared when it was finally decommissioned by the Department of Physics in the early 2000s. The colourful modifications to the original faux marble panel could represent damage to a classic instrument, or evidence of a remarkably rich provenance.

The U of T’s Chambers’ Micromanipulator is a particularly incomplete instrument, but it doesn’t seem to me like an object whose incompleteness is meaningful since we know so little about its past. Given the relative simplicity of its mechanism and missing parts, it seems reasonable to consider representing it as a complete object while acknowledging that, whatever the result, it will be only one possible representation.

As I’ve mentioned before, one of my goals is to recreate missing parts to produce a kind of sculptural representation of what the Chambers’ micromanipulator looked like when it was used—one, but certainly not the only, notion of a “complete object”. In future posts I hope to show that this kind of representation involves a creative process. The object itself seems to grow and change as your understanding of it increases. Parts become visible that weren’t visible before, or perhaps had been lost to view as the object became obsolete and the people who made and used it passed away.

A very early rendition of the “complete” Chambers’ Micromanipulator on display at a medical exhibition in 2012.

There is a second, more ambitious, goal that I’d also like to pursue. Historians of science sometimes attempt to recreate scientific effects from the past, a process that requires a considerable understanding of the technologies involved, but can produce insights that can’t be obtained any other way. In my next post, I’ll discuss the possibility of actually making the U of T Chambers’ micromanipulator functional again, using period equipment, to reproduce (something like) experiences that were last felt many decades ago.

Museum people talk about an object’s “provenance”, that is, its origin and past. The term comes from the world of fine art dealing, where it is essential to know the history of a work of art in order to establish its authenticity and legal ownership before selling it. It is a useful concept in thinking about any object because you can’t really understand an object without some idea of where it came from and how it was used. Depending on the circumstances, this evidence may or may not exist. Provenance research is especially valuable in interpreting scientific instruments, which take their meaning from laboratory research projects, are frequently unique or heavily modified, and which often belonged to larger experimental assemblies.

The previous post discussed some difficulties in understanding the history of the University of Toronto Chambers’ micromanipulator given the fact that various parts of it are missing. I noted that in order to understand exactly what is missing you need to understand its provenance. Here I’ll explain what I have and have not been able to discover about its past.

A place of origin

Several clues suggest that this instrument was acquired by the former University of Toronto School of Hygiene, which opened in 1927 in a new building on College Street. This has since been renamed the Fitzgerald building after Dr. John Gerald FitzGerald, who led Toronto’s emergence as a world centre of public health research over the first half of the 20th century (I have described the historical backdrop of the School in an earlier post.) I first found the instrument in a wooden box that also contained a yellowed offprint article written in 1922 by Robert Chambers and published in the Anatomical Record . This article is stamped “Department of Hygiene and Preventive Medicine”, one several departments that initially made up the School. It was probably used as a basic instruction manual.

First page of the offprint article identifying the object with the University of Toronto School of Hygiene.

This little clue is reassuring because it means that it is very unlikely that this object was a historical curiosity picked up by a researcher, or a piece of obsolete technology donated by a colleague and never used locally. It suggests that the instrument was purchased at some point between the opening of the School of Hygiene in 1927 and the mid 1930s. The instrument was available until the Second World War (if not slightly later), but the offprint article implies an earlier date because Chambers and his students had published more up-to-date guides by the early-to-mid 1930s.

The micromanipulator reappears in 1980 in a first-floor storage room in the Fitzgerald building. We can know this thanks to an inventory of historical scientific material, led by the Institute for the History and Philosophy of Science and technology (IHPST) that was carried out between (roughly) 1978 and 1981 in the hope these newly catalogued objects would become the basis for a University of Toronto science museum. The hundreds of cardboard file cards generated during this process survive as a snapshot of the U of T’s holdings at that point. The ’78 catalogue is a useful resource, though it also has a sad quality given the number of objects that have been lost since it was completed. The record for the manipulator isn’t especially enlightening. It mentions a “Dr. Wright” whom I haven’t been able to identify (cataloguers take note: first names are helpful).

The object’s catalogue record from the ’78 inventory.

At some point between 1980 and 2009, the micromanipulator journeyed a few blocks north from the Fitzgerald building to the office of the IHPST. There it joined (or maybe was joined by) a number of other unrelated medical objects under a table in the main office. Since the ’78 inventory, IHPST had been accumulating historical objects, donated by University faculty and the public, in the hope that a science museum would eventually be founded. These, like the micromanipulator, have since been incorporated into the University of Toronto Scientific Instruments Collection. The IHPST staff has generally kept very good records of this process (these records are gradually being organized into a UTSIC archive). Unfortunately, no information survives about the acquisition of the micromanipulator.

An important clue

In 1929, a doctoral student at the School of Hygiene named D. C. B. Duff published an article in The Journal of Laboratory and Clinical Medicine entitled “A Modification of the Orskov Single-Cell Technic“. The article describes a method for collecting individual bacteria in order to create colonies from single cells that required “an apparatus of the Chambers micromanipulator type”. Assuming that “an apparatus of the Chambers micromanipulator type” simply means “a Chambers’ micromanipulator” (the mechanism was patented), this probably indicates that the instrument was already being used in Duff’s lab to isolate bacteria using an earlier method described in 1922 by Morton C. Kahn, a colleague of Chambers at Cornell. Presumably, Duff believed his method to be more efficient than either of these earlier techniques.

Duff’s article doesn’t prove anything about this particular object, nor does it necessarily mean that the instrument was used for this one purpose only. It does give a plausible configuration of a University of Toronto’s Chambers’ micromanipulator, and with it a possible notion of what a “complete” representation might look like. The next post will describe various notions of a complete instrument and, consequently, several possible goals for this project

Most (possibly all) historical instruments are missing pieces, whether literally in the sense that parts have been lost, or metaphorically in the sense that there are gaps in our understanding about matters such as use or history (an instrument’s “provenance”). The University of Toronto Chambers’ micromanipulator is incomplete in both these senses; It is missing several important components, and it is lacking important documentation about where it came from and how it was used. Here, I’ll discuss some of the physical parts that are missing as well as the resulting difficulties that one might face in restoring this instrument to (or, perhaps, representing its condition when) it was used. Next time, I’ll discuss how gaps in the historical record also play into the ambiguity surrounding the instrument’s original form.

Surviving trade literature makes it possible to know, in a general sense, what could be missing from this instrument. I am grateful for a photocopy of Leitz Pamplet 1086, published in 1926 just after the instrument was first produced commercially, that was sent to me by the Countway Library of Medicine at Harvard University. This pamphlet gives a definitive list of the components initially available from Leitz, and consequently the possible configurations of an early model Chambers’ micromanipulator.

The object itself also supplies important clues. While it was possible to purchase this instrument with a single manipulator mechanism (or “movement”), this instrument has two—a more expensive and versatile configuration. Marks on the instrument’s base also reveal the locations and footprints of several missing components. The rectangular imprint of a syringe holder shows, for instance, that the instrument was operated with an optional microinjection apparatus.

It is fairly easy to identify many of these missing pieces, but it is very difficult to know exactly what they looked like. I have found surprisingly few images showing a complete instrument. As is often the case with early scientific instruments, professionally made technical illustrations that were created early in the instrument’s development and commercialization were reused until they were thoroughly outdated. Along with a few other images, they nevertheless show an instrument that was frequently updated and modified.

Consider, for instance, the syringe holder—the piece of the microinjection apparatus that would have left the rectangular mark in the photo above. Below are five depictions of this part (no. 6 belongs to a more modern Leitz micromanipulator that someone is currently selling on on ebay for $10,800)

Several depictions of Leitz syringe holders.

The syringe holder is a simple part—basically a sturdy clamp that places the plunger of a syringe within easy reach of the operator—yet each image shows a different design. Here is a 3d-printed version of the part that I made in 2012 with the help of Isaac Record at Semaphore Labs. Hopefully I’ll have an opportunity to do a second version with a few changes and a more convincing effort to match the grey-brown colour and smooth anodized surface of the instrument’s base.

As I’ll discuss in a future post, the Chambers’ micromanipulator (no doubt like many mass-produced technologies) was constantly being changed and improved, often in very subtle ways and for reasons that can only be guessed. In order to create a depiction of the completed instrument, you would need to show it at a particular moment in time that corresponds to the object that you’re working with. The less information is available, the more you will have to guess—the 3d printed piece above is really an embodied guess.

In addition to the difficulty of knowing what particular parts looked like, every instrument was configured according to the needs of local investigators. It was also equipped according to local resources and circumstances (available microscopes and so forth.) You can’t represent the instrument without representing one possible configurations at the expense of others. If you decide to represent what this instrument (i.e. the model purchased by the University of Toronto) was used for, you will need a great deal of knowledge about the instrument’s provenance—the topic of the next post.

I’ll finish here with a list of the pieces that could be seen as “missing” from the instrument as it was found. To put it another way, these are the parts that you would need to add to the existing instrument in order to create a reasonably convincing facsimile of this Chambers’ micromanipulator configured for use. I’ll eventually describe all of these bits in detail.

1) Pieces that would have come with the micromanipulator but are now missing:

– A syringe holder

– Two metal ‘pillars’ for holding flexible control shafts

– A small clamp for securing the flexible metal tube of the microinjection apparatus

– Luer fittings for the microinjection system

– Probably a holder for replacing microtools

2) Pieces that would have been supplied by the operator that were specifically necessary for this instrument:

– A glass moist chamber (most likely locally made, though available through Leitz)

– Locally made glass microtools, a 2cc glass Luer syringe

– A fine brass tube of the kind used for gas lighting and sealant for the microinjection system

3) Associated microscope equipment:

– A suitable research microscope (slightly modified with a split condenser)